This invention relates to apparatus and methods for the identification of sources of nuclear radiation within objects that may be opaque to other radiation. More specifically this invention relates to a high spatial resolution gamma ray detector employing focal plane array technology and a novel scintillation crystal radiation detection device.
There is a current need to identify nuclear sources within structures that are opaque to most non-nuclear radiation. The identification must be capable of being made from a remote distance in a non-destructive manner. Military uses include the identification of nuclear space mines near ballistic missile defense satellites. A device capable of such identification is also useful for nuclear weapons treaty verification since nuclear weapons have very definite nuclear material configurations and the combination of information about the spatial distribution of nuclear material within an object together with information about the emitted gamma-ray spectrum is often sufficient to characterize an object as a container for a nuclear weapon. To accomplish such identification requires a resolution of roughly 2 cm which is beyond the capability of current sensors and gamma-ray telescopes for any practical distance of the sensor from the object.
The invention can also be used to distinguish nuclear weapon containing reentry vehicles from decoys, when used in conjunction with a pulsed neutron source. The neutrons cause the emission of gamma-rays from the heavy reentry vehicle material but pass through decoys without comparable amounts of such emission. The gamma-rays are detected and discriminated by the present invention.